Both feeding and avoidance behaviors of frogs (Rana pipiens) are tested at: various blood levels of ethanol. Development of tolerance to chronic ethanol treatment is studied. Recording of single-units from optic tectum are made in paralyzed frogs with or without alcohol treatment. Effects of ethanol on both retinal and central inhibitory processes are estimated from quantitative measure of (a) unit habituation, and (b) surround-inhibition using double-stimuli. Postulated correlation between behavioral and physiological effects of ethanol can be so tested.